Final answer:
Jawless fishes lack jaws and paired fins, have a simple cartilaginous structure, and include species such as lampreys. Cartilaginous fishes have jaws, paired fins, and a cartilaginous skeleton, with members such as sharks and rays. Bony fishes have a true bony skeleton, a diverse group including ray-finned and lobe-finned species, and often have a swim bladder for buoyancy.
Step-by-step explanation:
The structures of jawless fishes, cartilaginous fishes, and bony fishes reflect their evolutionary history and adaptability to different environments. Jawless fishes are characterized by the absence of a jaw, and they often have a funnel-like mouth. They include species like lampreys and hagfishes. These organisms typically have a simple cartilaginous structure for support and lack paired fins that are seen in other fish classes. In contrast, cartilaginous fishes have a skeleton made of cartilage but possess jaws and paired fins.
This group includes sharks, rays, and skates and is known for their predatory nature and acute senses. Finally, bony fishes have a skeleton made of true bone, which is more rigid than cartilage. They are the most diverse group of fishes, including both ray-finned and lobe-finned species, and typically possess a swim bladder that helps regulate buoyancy.